JPH0510979Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial field of application] The present invention disperses the stress caused by pipe bending in the longitudinal direction of the pipe without concentrating it on one point.
Pipe bending that fits into the bent portion of the pipe to maintain the shape of the cross section of the pipe while bending the pipe into a smooth curved shape to prevent deformation of the cross section of the bent portion due to pipe bending. Regarding processing jigs.

[Conventional technology]

Conventional pipe bending jigs have been made of only coil springs made of a single layer of wire.

[The problem that the idea aims to solve]

However, when the jig is particularly fitted into the bent part of the pipe to support the bent part from the inside of the pipe, as shown in FIG. Due to the external force applied to the coil spring 2, the coil spring 2 tends to tilt in its longitudinal direction.
Even if the strength of the coil spring 2 itself is increased by making the wire thicker, it is difficult to prevent the coil from tilting in the longitudinal direction, so there is a drawback that it is difficult to improve shape retention for the cross-sectional shape of the bent part. It was hot.

The purpose of the present invention is to prevent the coil from tilting in the longitudinal direction due to external force applied in the radial direction, especially when the jig is fitted into the bent part. The point is to make it easier to improve the shape.

[Means to solve the problem]

The characteristic configuration of the pipe bending jig of the present invention is that a plurality of coil springs each having a different diameter are arranged such that one with a larger diameter surrounds one with a smaller diameter. The inner diameters of the outer coil springs adjacent to each other are set larger than the outer diameters of the inner coil springs, and the effects are as follows.

[Effect]

In other words, when fitting a jig into the bending part of a pipe, the stress that tends to be concentrated in one place due to the bending process of the pipe is dispersed in the longitudinal direction of the pipe by the elastic supporting force of the coil spring. However, as shown in FIG. 5, when the cross-sectional shape of the bent portion 3A attempts to deform into an ellipse as the pipe 3 is bent, the coil springs 2 adjacent to the inside and outside
Since the winding directions of B and 2A are different, the inner coil spring 2B is stretched and prevents the outer coil spring 2A from tilting due to the deformation of the cross-sectional shape. Compared to wound coil springs, it is easier to improve the shape retention of the cross-sectional shape of the bent part.

Furthermore _, in order to improve the shape retention of the cross-sectional shape of the bent portion, _for example, as shown in FIG. A jig 4 in which both the inner and outer coil springs 2B, 2A are set to be small or equal and arranged concentrically with the inner and outer coil springs 2B, 2A in close contact with each other,
It is also possible to bend the pipe 3 by fitting it inside the pipe 3, but in this case, as the pipe 3 is bent, the outer coil spring 2A is greatly stretched, and the inner coil spring 2B uses frictional resistance.
However, in order to prevent the bending of the pipe 3 with tension force, not only is a large force required to bend the pipe 3, but also it is difficult to reduce the bending radius r of the pipe 3. Because the inner diameter of the inner coil spring is set larger than the outer diameter of the inner coil spring, the outer coil spring contracts while being stretched as the pipe is bent.
Until they come into close contact with the inner coil spring, both the inner and outer coil springs bend together with the pipe while freely allowing relative sliding in the longitudinal direction, and the bending radius of the pipe can be reduced with a small force.

Also, when fitting a jig externally to the bending part of a pipe, the stress caused by bending the pipe is dispersed in the longitudinal direction of the pipe, while the stress applied in the radial direction is concentrated locally on the bending part. The stress is received by both the inner and outer coil springs to prevent deformation of the cross-sectional shape of the bent portion.

[Effect of idea]

Therefore, the pipe can be bent smoothly with a small radius of curvature, and the shape retention of the cross-sectional shape of the bent part can be easily improved, and the performance of the pipe bending jig can be improved with a simple structure. It became.

〔Example〕

Next, embodiments of the present invention will be described based on the drawings.

As shown in FIGS. 1 to 3, a coil spring 2 is formed by spirally winding a wire 1 without leaving any gaps, and two coil springs 2 each having a different diameter are formed.
are arranged so that the larger diameter one surrounds the smaller diameter one, and the winding directions of the adjacent coil springs 2 are made different, and the inner diameter R ₁ of the outer coil springs 2A adjacent to each other is set to Set the outer diameter R ₂ of the coil spring 2B to 0.1 mm to 0.5 mm larger than the outer diameter R 2 of both the inner and outer coil springs 2A and 2B.
is relatively movable in the longitudinal direction, and as shown in FIGS. 4 and 5, the bent portion 3A of the pipe 3
A jig for bending the pipe 3 is configured by fitting the pipe into the pipe 3 to prevent deformation of the cross section of the bent portion 3A during bending of the pipe.

Both ends of the outer coil spring 2A are bent inward as shown in FIGS. 2 and 3 to prevent the inner coil spring 2B from slipping out.

To use the pipe bending jig, after inserting the jig 4 into the pipe 3 to be processed up to the bending position (Fig. 4), as shown in Fig. 5, Using tool 4 as a dispersion member for pipe bending power, both sides of the bending position of pipe 3 are
After bending the pipe 3 into a curved shape by holding it with each hand, the cross-sectional shape of the bent portion 3A of the pipe 3 is slightly deformed, and the pipe 3 presses the outer circumference of the jig 4. Even if the jig 4 is pulled, the coil springs 2A and 2B will expand in the longitudinal direction and contract in diameter, and the jig 4 will be pulled out from inside the pipe 3 and return to its original state outside the pipe 3. It elastically returns to its shape.

[Another example]

The coil springs 2 may have two or more coil springs, each having a different diameter, arranged in multiple layers such that a larger diameter one surrounds a smaller diameter one, and the inner diameter R ₁ of the outer coil spring 2A If the difference between the outer diameter R ₂ of the coil spring 2B and the inner coil spring 2B is 0.1 mm or less, it will be difficult for both coil springs 2A and 2B to move relative to each other in the longitudinal direction, and if the difference is 0.5 mm or more,
Due to poor shape retention for the pipe 3 cross-sectional shape,
Although the optimal size is between 0.1mm and 0.5mm,
As long as the inner diameter R ₁ is set larger than the outer diameter R ₂ , it can be used.

The jig 4 may be fitted onto the outside of the pipe 3 and used to maintain the cross-sectional shape of the pipe 3 during bending of the pipe 3.

One end side of the inner coil spring 2B is
The coil spring 2B is formed into a rod shape and is formed as a grip part 5 when inserting the jig 4 into the pipe 3.
To prevent the grip part 5 side of the coil spring 2A from coming off the coil spring 2A, as shown in Fig.
Instead of bending the end portion and winding it around the grip portion 5, the end portion may be simply bent as shown in FIG.

As shown in FIG. 7, the rod-shaped gripping portion 5 is provided with a scale 6 so that it can be determined to what position the jig 4 has been inserted into the pipe 3. This makes it possible to accurately and easily position the jig 4 to the position where the pipe 3 is to be bent while looking at the scale 6.

Note that although reference numerals are written in the claims section of the utility model registration for convenience of comparison with the drawings, the present invention is not limited to the structure of the attached drawings by such entry.

[Brief explanation of the drawing]

The drawings show an embodiment of the pipe bending jig according to the present invention, and FIG. 1 is a front view showing a partial cross section;
Figure 2 is a left side view, Figure 3 is a right side view, Figure 4 is an explanatory diagram showing the process of inserting the jig into the pipe, and Figure 5 is a diagram showing the state of bending the pipe with the jig inserted inside. Explanatory drawings, FIG. 6 is a left side view of another embodiment, FIG. 7 is a front view of another embodiment, and FIG. 8 is a partial sectional view showing a state in which a pipe is bent using a conventional jig. , FIG. 9 is a front view showing a partial cross section of a jig showing a comparative example. 2, 2A, 2B...Coil spring, 3...
Pipe, 3A...Bending part, R ₁ ...Inner diameter, R ₂
...Outer diameter.

Claims (1)

[Claims for Utility Model Registration] 1. A pipe bending jig which is fitted into a bending portion 3A of a pipe 3 to prevent deformation of the cross section of the bending portion 3A due to pipe bending, Multiple coil springs 2 with different diameters
are arranged in such a way that one with a larger diameter surrounds one with a smaller diameter, and the winding directions of the coil springs 2 are made different between adjacent ones, so that the inner diameter of the outer coil springs 2A that are adjacent to each other is
A pipe bending jig in which R ₁ is set larger than the outer diameter R ₂ of the inner coil spring 2B. 2 The difference between the inner diameter R ₁ and the outer diameter R ₂ is 0.1 mm to 0.5 mm.
The pipe bending jig according to claim 1, wherein the pipe bending jig is set to .